A flexible acoustic mismatched backing for a flooded water acoustic transducer

Abstract

The application discloses an overflow water acoustic transducer with a flexible acoustic mismatch body backing, comprising an overflow transducer and a flexible acoustic mismatch body, wherein the flexible acoustic mismatch body is located inside a radiation surface of the overflow transducer; the flexible acoustic mismatch body is a cylindrical air bag and comprises a rubber layer and a fiber mesh layer from outside to inside, and compressed air is filled into the fiber mesh layer to make the maximum pressure bearing in the flexible acoustic mismatch body not less than 5 MPa. The application sets the flexible acoustic mismatch body inside the radiation surface of the overflow transducer, sets the rubber layer and the fiber mesh layer from outside to inside of the cylindrical air bag of the flexible acoustic mismatch body, and balances the hydrostatic pressure of deep water by filling the compressed air into the flexible acoustic mismatch body. Meanwhile, the fiber mesh layer has a high acoustic transmission efficiency when shearing vibration, most of the acoustic waves are transmitted through the fiber mesh layer and have phase jump, the phase of the sound pressure of the acoustic waves emitted by the radiation surface inside the overflow transducer is opposite to that of other acoustic waves, the dipole vibration mode of the overflow transducer is greatly weakened, and the energy conversion efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic transducer technology, and more particularly to an overflow underwater acoustic transducer with a flexible acoustic mismatch backing. Background Technology

[0002] Underwater acoustic transducers are devices used to convert electroacoustic energy underwater. With the rapid development of modern sonar technology and the continuous expansion of underwater acoustic applications, the performance requirements for underwater acoustic transducers are also increasing. Currently, transmitting transducers with characteristics of deep water, low frequency, wide bandwidth, small size, and high power are the main research direction for underwater acoustic transmitting transducers. However, the main design challenge of deep-water low-frequency transducers lies in the fact that air-backed low-frequency transducers have low-stiffness vibration structures that struggle to maintain normal operation under the high pressure differential environment of deep water; furthermore, although overflow transducers do not need to withstand the pressure difference generated by hydrostatic pressure, their dipole vibration modes suffer from low energy conversion efficiency. Summary of the Invention The present invention provides an overflow underwater acoustic transducer with a flexible acoustic mismatch backing to solve the above-mentioned technical problems.

[0003] To achieve the above objectives, the technical solution of the present invention is as follows: An overflow underwater acoustic transducer backed by a flexible acoustic mismatch includes an overflow transducer and a flexible acoustic mismatch, the flexible acoustic mismatch being located inside the radiating surface of the overflow transducer; the flexible acoustic mismatch is a cylindrical air bladder, and it includes a rubber layer and a fiber mesh layer from the outside to the inside, the fiber mesh layer being filled with compressed air so that the maximum pressure inside the flexible acoustic mismatch is not less than 5MPa.

[0004] Preferably, the fiber web layer is made of aramid fiber web, nylon fiber web or carbon fiber web material.

[0005] Preferably, the flexible acoustic mismatch body has rubber layers on both ends, and at least one end face is provided with an air nozzle that can be inflated into the flexible acoustic mismatch body.

[0006] Preferably, there are multiple flexible acoustic mismatches, which are arranged in parallel and at intervals, and are parallel to the radiation surface inside the overflow transducer.

[0007] Preferably, the overflow transducer is a bending transducer, a bending disc transducer, a bending slat transducer, or a slotted annular transducer.

[0008] Preferably, the overflow transducer is an electric transducer or an electromagnetic transducer.

[0009] Preferably, the overflow transducer is a bending transducer, with mounting plates at both ends of the shell of the bending transducer. The mounting plates are fixed to the shell by locking screw assemblies, and the flexible acoustic mismatch body is fixed on the mounting plates.

[0010] Preferably, a decoupling pad is provided between the mounting plate and the housing.

[0011] Beneficial effects: This application discloses an overflow underwater acoustic transducer with a flexible acoustic mismatch backing. By setting a flexible acoustic mismatch inside the radiating surface of the overflow transducer, the flexible acoustic mismatch of the cylindrical airbag is provided with a rubber layer and a fiber mesh layer from the outside to the inside. Compressed air is filled into the flexible acoustic mismatch to balance the hydrostatic pressure brought by deep water. At the same time, the fiber mesh layer has a high sound transmission efficiency when shearing, and most of the sound waves pass through the fiber mesh layer and undergo a phase jump, which is opposite to the sound pressure phase of other sound waves emitted from the radiating surface inside the overflow transducer. This greatly weakens the dipole vibration mode of the overflow transducer and thus improves the energy conversion efficiency. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of a flexible acoustic mismatch backing for an overflow water acoustic transducer disclosed in this invention. Figure 2 This is a schematic diagram of the structure of an overflow water acoustic transducer with a flexible acoustic mismatch backing disclosed in this invention. Figure 3 This invention discloses a burst test pressure test table for a flexible acoustic mismatch backing overflow water acoustic transducer. Figure 4 This is a schematic diagram of the structure of an overflow water acoustic transducer with a flexible acoustic mismatch backing disclosed in this invention, which uses a bending and tensioning transducer. Figure 5 The transmitted voltage response curve is obtained from the prototype test.

[0014] In the figure: 1. Flexible acoustic mismatch body; 11. Rubber layer; 12. Fiber mesh layer; 13. Compressed air; 2. Housing; 3. Mounting plate; 4. Locking screw assembly; 5. Decoupling pad; 61. First transition block; 62. Second transition block; 63. Piezoelectric ceramic; 64. Electrode sheet; 65. Insulating sleeve; 7. Prestressed screw. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] An overflow underwater acoustic transducer with a flexible acoustic mismatch backing, such as Figure 1 and Figure 2 As shown, the device includes an overflow transducer and a flexible acoustic mismatch 1, with the flexible acoustic mismatch 1 located inside the radiating surface of the overflow transducer. The flexible acoustic mismatch 1 is a cylindrical airbag, and from the outside to the inside, it includes a rubber layer 11 and a fiber web layer 12. Compressed air 13 is filled into the fiber web layer 12 so that the maximum pressure inside the flexible acoustic mismatch 1 is not less than 5 MPa. By setting the flexible acoustic mismatch 1 inside the radiating surface of the overflow transducer, the flexible acoustic mismatch 1 of the cylindrical airbag is provided with a rubber layer 11 and a fiber web layer 12 from the outside to the inside. The fiber material undergoes high-speed stretching during melt spinning, and the molecular chains are highly oriented along the fiber axis, resulting in its transverse modulus being lower than its axial modulus. The fiber web layer 12, made of fiber material with anisotropic mechanical properties, has high strength under radial stretching and high sound transmission efficiency under shear vibration. The flexible acoustic mismatch 1 is designed as a cylindrical airbag. Its annular structure can transfer radial gas pressure into uniform tangential stress, which is applied axially to the fiber mesh layer 12. The high axial modulus of the fiber mesh layer 12 enables the flexible acoustic mismatch 1 to withstand the high pressure of high-pressure gas. After the flexible acoustic mismatch 1 is filled with compressed air, it can balance the hydrostatic pressure brought by deep water. Because the radial stiffness of the fiber mesh layer 12 differs greatly from that of the rubber layer 11, and the Poisson's ratio of the rubber layer 11 is very high, the vibration of the fiber mesh layer 12 exhibits complex shear components. As a result, the acoustic impedance generated by the shear vibration of the fiber mesh layer 12 is comparable to that of water. Driven by the radial sound pressure of the inner radiating surface, the flexible acoustic mismatch 1 causes the fiber mesh layer 12 to undergo shear vibration with high sound transmission efficiency. This allows most of the sound waves at the rubber-fiber interface to pass through the fiber mesh layer 12 and undergo total reflection at the fiber-air interface, achieving a 180° phase jump. These total reflection sound waves are out of phase with the sound pressure of other sound waves emitted by the inner radiating surface at the same instant. This confines the sound power radiated by the inner radiating surface into the overflow transducer in the form of standing waves, significantly reducing the dipole vibration mode of the overflow transducer and thus improving the electroacoustic energy conversion efficiency.

[0017] Preferably, the flexible acoustic mismatch 1 is a slender cylindrical airbag, the rubber layer 11 is made of sound-permeable rubber material, and the fiber mesh layer 12 is made of aramid fiber mesh, nylon fiber mesh or carbon fiber mesh material. This application utilizes the high axial modulus and low transverse modulus of the fiber, the high Poisson's ratio of the rubber and the low characteristic impedance of the high-pressure air. The combination of the fiber mesh layer 12, the rubber layer 11 and the high-pressure air can not only improve the pressure resistance of the flexible acoustic mismatch 1, but also ensure that its working mechanism does not weaken as the frequency decreases. As a result, the conversion efficiency of the designed overflow underwater acoustic transducer is higher than that of ordinary overflow underwater acoustic transducers.

[0018] Preferably, the flexible acoustic mismatch body 1 has rubber layers 11 on both ends, and at least one end face is provided with an air nozzle for inflating the flexible acoustic mismatch body 1 to the required pressure. Figure 3 As shown, this is a burst test pressure measurement table for the flexible acoustic mismatch 1 in this embodiment. The horizontal axis represents time, and the vertical axis represents test pressure. It can be seen from the figure that the burst pressure of the test piece of the flexible acoustic mismatch 1 in this embodiment can reach 8.5 MPa, which meets the requirements for stable operation in deep-water environments.

[0019] Preferably, there are multiple flexible acoustic mismatches 1, which are arranged in parallel and at intervals. The flexible acoustic mismatches 1 are parallel to the radiation surface inside the overflow transducer. The cooperation of multiple flexible acoustic mismatches 1 can improve the hydrostatic pressure resistance of the entire overflow transducer.

[0020] Preferably, the overflow transducer is a bending transducer, a bending disk transducer, a bending slat transducer, or a slotted annular transducer. The flexible acoustic mismatch 1 in this application is applicable to most transducer structures and has broad application prospects, and can be used in underwater acoustic detection, countermeasures, communication, measurement, and marine resource exploration.

[0021] Preferably, the overflow transducer is an electric transducer or an electromagnetic transducer.

[0022] Preferably, such as Figure 4 As shown, the structure of the bending transducer is used as an example for explanation. The shell 2 of the bending transducer is a traditional type IV bending transducer shell. The shell 2 is made of titanium alloy material and the total length of the bending transducer is about 130mm.

[0023] The tension transducer includes an oscillator assembly, which comprises a first transition block 61, a second transition block 62, a piezoelectric ceramic 63, an electrode plate 64, and an insulating sleeve 65. The first transition block 61 and the second transition block 62 are made of titanium alloy. During the assembly of the tension transducer, pressure is applied to both ends of the short shaft of the housing 2 to increase the length of the long shaft. The oscillator assembly is then placed in the housing 2, and the pressure is released. At this time, prestress is applied using a prestressing screw 7 to fix the oscillator assembly in the housing 2, achieving a rigid connection between the oscillator assembly and the housing 2. Mounting plates 3 are provided at both ends of the housing 2 of the tension transducer. The mounting plates 3 are fixed to the housing 2 by locking screw assemblies 4, and the flexible acoustic mismatch body 1 is fixed on the mounting plates 3.

[0024] Specifically, the mounting plate 3 is provided with limiting holes, and the air nozzles at both ends of the flexible acoustic mismatch 1 extend into the limiting holes. The two mounting plates 3 clamp and fix the flexible acoustic mismatch 1.

[0025] Preferably, a decoupling pad 5 is provided between the mounting plate 3 and the housing 2.

[0026] like Figure 5 The figure shows the short-axis transmission voltage response curves of the prototype in this embodiment under different backing conditions. In the figure, the horizontal axis represents frequency, and the vertical axis represents transmission voltage response. It can be seen from the figure that the response of the flexible acoustic mismatch as a backing is higher than that of the full overflow, indicating that the flexible acoustic mismatch successfully reduces the dipole effect of the overflow bending transducer. It can also be seen from the figure that the response of the flexible acoustic mismatch at the resonance peak of the first bending mode is lower than that of the sound-absorbing rubber backing. This is because the nylon fiber mesh layer increases the damping of the transducer, but the maximum operating depth of the flexible acoustic mismatch is much greater than that of the sound-absorbing rubber backing. It can also be seen from the figure that the flexible acoustic mismatch backing has lower damping and performs better at resonance than the flexible acoustic mismatch backing. However, the modes of the flexible acoustic mismatch itself are not suppressed by the high damping of nylon, thus impairing the broadband performance of the transducer; furthermore, the flexible acoustic mismatch deforms drastically with depth changes, making it unsuitable for deep-water environments. In summary, flexible acoustic mismatches, due to their working mechanism being almost unaffected by frequency, exhibit broadband emission performance similar to that of sound-absorbing rubber backings when used as transducers. The high-pressure gas inside allows the transducer's performance to remain relatively stable under depth variations, and the overflow structure provides better heat dissipation compared to air-backed structures. As a result, schemes using flexible acoustic mismatches as backings have better overall performance and broad application prospects.

[0027] The response of the flexible acoustic mismatch backing is higher than that of the full overflow, indicating that the flexible acoustic mismatch successfully reduces the dipole effect of the overflow bending transducer. However, the response of the flexible acoustic mismatch backing at the resonance peak of the first bending mode is lower than that of the sound-absorbing rubber backing. This may be because the nylon reinforcement layer increases the damping of the transducer, but the maximum operating depth of the flexible acoustic mismatch is much greater than that of the sound-absorbing rubber. The flexible acoustic mismatch backing has lower damping and performs better at resonance than the flexible acoustic mismatch backing, but its own modes are not suppressed by the high damping of the nylon reinforcement layer, thus impairing the broadband performance of the transducer. Furthermore, the flexible acoustic mismatch deforms drastically with depth changes, making it unsuitable for deep-water environments. Because the working mechanism of the flexible acoustic mismatch is almost unaffected by frequency, the broadband emission performance of the transducer under its backing is similar to that of the sound-absorbing rubber backing. The high-pressure gas inside can keep the transducer performance relatively stable under depth changes, and the overflow structure is easier to dissipate heat than the air backing structure. Therefore, this design scheme can be considered to have a wide range of application prospects.

[0028] The working principle of the device in this application is as follows: When the overflow acoustic transducer is working, an alternating current load is applied to the piezoelectric ceramic 63 through the electrode plate 64. The piezoelectric ceramic 63 crystal has a piezoelectric effect, causing the entire piezoelectric crystal stack to produce longitudinal stretching vibration. Through mechanical coupling with the shell 2, the inner and outer sides of the shell 2 simultaneously radiate acoustic signals with opposite phases. Part of the acoustic signal radiated from the inner radiating surface of the shell 2 undergoes total reflection in the flexible acoustic mismatch body 1 and achieves a 180° phase jump. These total reflected sound waves are out of phase with the sound pressure of other sound waves emitted by the inner radiating surface at the same instant, thereby confining the acoustic power radiated from the inner radiating surface into the overflow acoustic transducer in the form of a standing wave. This allows the overflow transducer radiating surface to maintain a certain energy conversion efficiency without having to withstand high hydrostatic pressure on one side.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An overflow underwater acoustic transducer with a flexible acoustic mismatch backing, characterized in that, The system includes an overflow transducer and a flexible acoustic mismatch (1), wherein the flexible acoustic mismatch (1) is located inside the radiating surface of the overflow transducer; the flexible acoustic mismatch (1) is a cylindrical airbag, and it includes a rubber layer (11) and a fiber mesh layer (12) from the outside to the inside, wherein compressed air (13) is filled into the fiber mesh layer (12) so that the maximum pressure inside the flexible acoustic mismatch (1) is not less than 5MPa; the fiber mesh layer (12) is made of aramid fiber mesh, nylon fiber mesh or carbon fiber mesh material, and the fiber mesh layer (12) has With anisotropic mechanical properties, the vibration of the fiber mesh (12) exhibits complex shear components, resulting in an acoustic impedance generated by the shear vibration of the fiber mesh (12) being comparable to that of water. The flexible acoustic mismatch (1) is driven by the radial sound pressure of the inner radiating surface, and the shear vibration of the fiber mesh (12) has a high sound transmission efficiency, allowing most of the sound waves at the rubber-fiber interface to pass through the fiber mesh (12) and undergo total reflection at the fiber-air interface to achieve a 180° phase jump.

2. The overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to claim 1, characterized in that, The flexible acoustic mismatch (1) has rubber layers (11) on both ends, and at least one end is provided with an air nozzle that can be inflated into the flexible acoustic mismatch (1).

3. The overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to claim 1, characterized in that, The flexible acoustic mismatch (1) consists of multiple units, which are arranged in parallel and at intervals. The flexible acoustic mismatch (1) is parallel to the radiation surface inside the overflow transducer.

4. An overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to any one of claims 1-3, characterized in that, The overflow transducer can be a tension transducer, a curved disc transducer, a curved slat transducer, or a slotted annular transducer.

5. The overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to claim 4, characterized in that, The overflow transducer can be either an electric transducer or an electromagnetic transducer.

6. An overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to any one of claims 1-3, characterized in that, The overflow transducer is a bending transducer. The shell (2) of the bending transducer is provided with mounting plates (3) at both ends. The mounting plates (3) are fixed to the shell (2) by locking screw assembly (4). The flexible acoustic mismatch body (1) is fixed on the mounting plate (3).

7. The overflow underwater acoustic transducer with a flexible acoustic mismatch backing according to claim 6, characterized in that, A decoupling pad (5) is also provided between the mounting plate (3) and the housing (2).

Images